Truthfully, I can't see this idea happening, though ten points for creativity. This doesn't have a big use other than decorative purposes for the community. Furthermore, it would nearly destroy much of the value of some already existing rare items (i.e. the Impossiball, the White Point Star, and Sarah Jane's Warpstar). Furthermore, as others have said, part of the reason promos are special is because they cannot be obtained naturally. Being able to pay to have enchantments added to any old item (something not able to be done naturally) might take away from the value and entertainment centered around promotional and event items.

Correct, and we're a survival server, so let's not have this service and just leave it to the odd EMC custom item so that it is more special and actually worth something - and also keep it so that the majority of enchantments genuinely work on the item without lots of random ones like this service would bring